Bollettino epidemiologico nazionale

A Survey on the Use of Seatbelts in the City of Genoa

Claudio Culotta¹, Rosamaria Cecconi¹, Gianna Ferrando¹ and the participants of the Applied Epidemiology Course*, Genoa, June, 2002.

¹Local Health Authority 3 Genovese (Genoa, Liguria)

In Italy, approximately half of traffic-related emergency room visits and deaths resulting from involve motorists (1). Seatbelts have been demonstrated to be effective in reducing the frequency and severity of  injury and death.

In Liguria, a region in northwest Italy, the current use of seatbelts is estimated to be approximately 30%, leaving considerable room improvement. Fortunately, activities designed to improve seat belt use have the advantage, compared with many other public health interventions, of having an objective that is specific, concrete, and easily measurable, thereby facilitating the evaluation of preventive efforts.

To obtain baseline data prior to beginning an intervention and to obtain some basic information about factors related to non-use, the Prevention Department of the Local Health Authority 3 Genovese decided to conduct an observational study to collect information on prevalence of seatbelt use. The specific objectives of the study were to estimate the prevalence of seatbelt use among drivers and front-seat passengers, to ascertain any differences in use associated with sex, age, type of road, type of vehicle (public/private) and to assess infant car seat use for children £4 years of age.

The estimates were developed on the basis of direct observation of the behavior of the drivers and passengers in 12 urban intersections and at the exit of the elevated roadway. The maps of the commune of Genoa contained in supplement of the telephone directory were used for sampling. The directory contains an overall map of the city that is divided into 32 numbered squares as well as detailed maps for each of the 32 squares. The detailed maps are divided into variable numbers of squares identified by numbers on the horizontal axis and letters on the vertical axis. Twelve of the 32 squares from the overall map were randomly selected for inclusion in the survey. The more detailed maps were used to select the specific observation points; after eliminating squares that did not contain intersections, the remaining squares were numbered and one was chosen at random. Within the selected squares, the busiest intersection was chosen.

Two observers were stationed at each observation site. Each time that the stop light turned red, they observed the characteristics and seat belt use of persons in the first three cars. Data collection was done over a 30-minute period from 7:45 to 8:15 on Tuesday, June 11; the observation time was established such that the total number of study observations would be at least 650 cars.

On a specially developed data collection form, information was recorded on the site of the observation (urban street or elevated highway), the designated number of the observation site, the type of vehicle (public or private), the sex and estimated age of the driver and front-seat passenger (5-17 years, 18-30 years, and >30 years), and whether or not their seat belts were fastened. In addition, regardless of location in the car, the use of infant car seats was noted for all children estimated to be 4 years of age or younger.

The data were analysed with Epi-Info 6.04d. Confidence intervals were calculated using C-sample, which took into account the design effect resulting from the cluster survey methods employed.

Observations were recorded for a total of 900 cars and 1155 persons. Five percent of the cars were public vehicles (taxis, police cars, etc) in which the use of seat belts is not obligatory. Eighty-seven percent of the 1155 persons were observed on urban streets and the remaining 13% on the elevated highway. Two-thirds (65%) were men, and 78% were drivers; 21% were estimated to be between 18 and 30 years, and 78% over 30 years. There were only 11 children years of age in the sample and only 7 in the 4-17 year age group.

The overall use of seatbelts was 31.6%. Use was higher in women (38%; 95% confidence intervals (CI) 33-43% than in men (27%; 95% CI 24-31%). Younger persons were less likely to wear seatbelts than older adults [28% (95% CI 22-34%) versus 32% (95% CI 29-35%)]. When results were stratified by sex, age differences in seat belt uses increased among men (19% for those 18-30 years versus 29% for those 30 years and over), while among women, those who were younger had a higher prevalence of seat belt use (41% versus 37%).

No significant differences were noted in seatbelt use between drivers (30%) and front-seat passengers (34%) (Table). With respect to the type of road, use was significantly higher on the elevated highway (46%) than it was on urban streets (30%).

Use of infant safety seats in children 0-4 years was high (91%), although only 11 children in this age group were observed in the study. Seat belt use was very low in public vehicles (14%).

In our study, data collection was conducted early in the morning during a period when the schools were closed for the summer. Thus the population observed was composed of a specific segment of the general population, namely adults who were on their way to work. This limited our ability to examine seat belt use in the 5-17 year age group and car seat use in the 0-4 year age group and also limited the study’s generalizability to the general population of Genoa.

In spite of these limitations, our results provide a basis for an intervention program designed to improve seatbelt use in the Local Health Authority and the Region and confirms that seat belt use in Genoa is very low. In particular, young men constitute a high-risk group.

A further important finding was that the use of seatbelts on the elevated highway was higher than on urban streets. This suggests that behavior of drivers is conditioned by their perception of risk.

* Participants, Applied Epidemiology Course, Genoa, June 2002: Caniffi Alberto; Ferrando Gianna; Gallo Daniela; Poltrini Gabriella; Rosselli Roberto; Blanchi Ines; Bozano Paolo Francesco; Costa Marcella; Pascali Federica; Penco Gabriella; D'Aste Ersilia; Businelli Attilio; Rulfi Antonella; Soru Elena Giustina; Serra Massimo; Macrina Giuseppe; Alassio Paolo; Canova Alessandro; Orefice Giovanni; Parodi Roberto; Varagona Giuseppe; Corsini Massimo; Astegiano Giovanni; Capurro Marcello; Mazzarello Elena; Meccoli Nadia; Hossein Javad; Gaggero Domenico

Editorial Note

Giordano Biserni¹ e Marco Giustini²

¹ President, Association of the Supporters and Friends of the Road Police, Bologna

² Laboratory of Epidemiology and Biostatistics, Istituto Superiore di Sanità, Rome

Years after the introduction of laws requiring seat belt use in Italy, use remains unacceptably low. To date, Italy has not managed to improve coverage past a mean level of 30-40%, with some areas of the country reporting use as low as 15-20%. It cannot be denied that the battle of seatbelt use has yet to be won despite all the educational efforts and the stated policies of “zero tolerance”; each year, the failure to win this war results in thousands of victims.

The effectiveness of seatbelts and airbags in reducing injury and death has been demonstrated repeatedly. Most recently, the University of Washington has presented its dramatic findings of a study of 58,000 accidents, in which the use of seatbelts limited the risk of death by 64%. The use of airbags alone (which are relied upon by many of those who refuse to use their seat belts) limited the risk by only 8% (2). The combined use of seabelts and airbags reduced risk by 68%.

The study done in Genoa demonstrates a problem that has been seen throughout Italy. The prevalence of seatbelt use observed in the capital of Liguria is in fact similar to the mean value for Italy based on the national seatbelt surveillance system (ULISSE; 3). As has been previously demonstrated by the ISS, the use of seatbelts represent one of the most effective preventive practices and furthermore their effectiveness can be evaluated in the short term. If in Genoa the seatbelt use were to increase to 75% (the mean value for Europe), the benefits could be estimated as follows: 10 fewer deaths, 20 fewer persons with disabling injuries, and 200 fewer hospitalisations per year; if this same level could be reached at national level, there would be 1200 fewer deaths, 2400 fewer serious injuries, and 24,000 fewer hospitalisations.

Studies conducted in the Unites States demonstrate that the introduction and application of a law that mandates the use of seatbelts increased on use an average of 33% with a 9% reduction in mortality (4). In Italy, there is no need for further laws; Article 172 of the traffic laws state that all occupants of cars must wear seatbelts, with few exemptions. This same Article specifies the sanctions for violators. Closer collaboration is apparently needed between public health institutions and law authorities such that the effects of the existing law can be fully realized.

• Progetto SISI, Istituto Superiore di Sanità.
• Cummings P, McKnight B, Rivara FP, Grossman DC. Association of driver air bags with driver fatality: a matched cohort study. BMJ 2002, May 11; 324 (7346): 1119-22
• Sistema ULISSE: Progetto DATIS - Accordo Quadro Ministero delle Infrastrutture e Trasporti - Istituto Superiore di Sanità
• CDC. Motor-vehicle occupant injury: strategies for increasing use of child safety seats, increasing use of safety belts, and reducing alcohol-impaired driving. A report on recommendations of the Task Force on Community Preventive Services. MMWR. 2001: 50 (No. RR-7); 1-13.